A difficulty encountered with fragranced personal cleansing compositions is that the fragrance oils are solubilized within the surfactant micelles such that they either remain micellized or enter the continuous aqueous phase. Either way, the result is that they are typically rinsed away during the washing process rather than being deposited onto the skin as intended.
Previous work has employed a number of methods to counter this effect. One approach discussed in EP 0554024 has been to reduce solubilization of the perfume oil in the surfactant phase by adding an oil phase in which the perfume oils may reside. As a result of the oil's natural hydrophobicity, that oil phase, including the perfume oil, may deposit relatively well onto skin. A similar approach is discussed in WO 03/015736, which relates to the dissolution of the perfumes in a water-immiscible silicone phase. Again, the naturally hydrophobic silicone phase may lead to improved deposition of the fragrance oil onto skin. These approaches involve the inclusion of an additional material to the formulation to enhance fragrance delivery. That additional material may, however, have negative implications for the overall performance of the formulation, such as the lather profile.
An alternative approach discussed in WO 97/48374, WO 97/48375 and WO 97/48378, has been to form coacervates between anionic surfactant and cationic polymers, which coacervates are allegedly capable of entrapping the perfume, depositing on the skin and thus enhancing perfume deposition.
A further alternative discussed in US 2003/166497, US 2003/166498 and US 2003/166499 has been to design the perfume/surfactant system such that, on dilution, micelles are designed to disappear due to their high Critical Micelle Concentration (CMC), and deliver fragrance bloom. After blooming from the micelles, the perfume materials enter the water continuous phase and may be washed away during rinsing. Once again, the surfactant phase is essentially a micellar phase.
Additional approaches employing various surfactants are described in GB 1440975, EP 117135, EP 23676, U.S. Pat. No. 5,035,826, U.S. Pat. No. 5,661,189, US 2009/0312223, and EP 0347199.